What is vitamin D deficiency?
Vitamin D deficiency means that you do not have enough vitamin D in your body. Vitamin D is unique because your skin actually produces it by using sunlight. Fair-skinned individuals and those who are younger convert sunshine into vitamin D far better than those who are darker-skinned and over age 50.
Why is vitamin D so important?
Vitamin D is one of many vitamins our bodies need to stay healthy. This vitamin has many functions, including:
You are watching: Why is vitamin d important
- Keeping bones strong: Having healthy bones protects you from various conditions, including rickets. Rickets is a disorder that causes children to have bones that are weak and soft. It is caused by a lack of vitamin D in the body. You need vitamin D so that calcium and phosphorus can be used to build bones. In adults, having soft bones is a condition called osteomalacia.
- Absorbing calcium: Vitamin D, along with calcium, helps build bones and keep bones strong and healthy. Weak bones can lead to osteoporosis, the loss of bone density, which can lead to fractures. Vitamin D, once either taken orally or from sunshine exposure is then converted to an active form of the vitamin. It is that active form that promotes optimal absorption of calcium from your diet.
- Working with parathyroid glands: The parathyroid glands work minute to minute to balance the calcium in the blood by communicating with the kidneys, gut and skeleton. When there is sufficient calcium in the diet and sufficient active Vitamin D, dietary calcium is absorbed and put to good use throughout the body. If calcium intake is insufficient, or vitamin D is low, the parathyroid glands will ‘borrow’ calcium from the skeleton in order to keep the blood calcium in the normal range.
What are the health effects of vitamin D deficiency?
Getting enough vitamin D may also play a role in helping to keep you healthy by protecting against the following conditions and possibly helping to treat them. These conditions can include:
- Heart disease and high blood pressure.
- Infections and immune system disorders.
- Falls in older people.
- Some types of cancer, such as colon, prostate and breast cancers.
- Multiple sclerosis.
What are the sources of vitamin D?
You can get vitamin D in a variety of ways. These can include:
- Being exposed to the sun. About 15-20 minutes three days per week is usually sufficient.
- Through the foods you eat.
- Through nutritional supplements.
What does sunlight have to do with getting enough vitamin D?
There are health benefits of sunlight. Vitamin D is produced when your skin is exposed to sunshine, or rather, the ultraviolet B (UV-B) radiation that the sun emits. The amount of vitamin D that your skin makes depends on such factors as:
- The season: This factor depends a bit on where you live. In areas such as Cleveland, OH, the UV-B light does not reach the earth for six months out of the year due to the ozone layer and the zenith of the sun.
- The time of day: The sun’s rays are most powerful between 10 a.m. and 3 p.m.
- The amount of cloud cover and air pollution.
- Where you live: Cities near the equator have higher ultraviolet (UV) light levels. It is the UV-B light in sunlight that causes your skin to make vitamin D.
- The melanin content of your skin: Melanin is a brown-black pigment in the eyes, hair and skin. Melanin causes skin to tan. The darker your skin, the more sun exposure is needed in order to get sufficient vitamin D from the sun.
What does your diet have to do with getting enough vitamin D?
Vitamin D doesn’t occur naturally in many foods. That’s why certain foods have added vitamin D. In fact, newer food nutrition labels show the amount of vitamin D contained in a particular food item.
It may be difficult, especially for vegans or people who are lactose-intolerant, to get enough vitamin D from their diets, which is why some people may choose to take supplements. It is always important to eat a variety of healthy foods from all food groups. The vitamin content of various foods is shown in the following table.
Vitamin D content of various foods
FoodVitamin D content in International Units (IUs) per servingCod liver oil, 1 tablespoon1360Swordfish, cooked, 3 ounces566Salmon (sockeye) cooked, 3 ounces447Tuna, canned in water, drained, 3 ounces154Orange juice fortified with vitamin D, 1 cup137Milk, vitamin-fortified, 1 cup115-124Yogurt, fortified with 20% of the daily value of vitamin D, 6 ounces80Sardines, canned in oil, drained, 2 sardines46Liver, beef, cooked, 3 ounces42Egg yolk, 1 large41Cereal, fortified with 10% of the daily value of vitamin D, 1 cup40Cheese, Swiss, 1 ounce6
Source: Vitamin D. Health Professionals. Dietary Supplement Fact Sheet. National Institutes of Health. Office of Dietary Supplements. August 7, 2019.
It is important to check product labels, as the amount of added vitamin D varies when it is artificially added to products such as orange juice, yogurt and margarine.
How much vitamin D do you need?
In healthy people, the amount of vitamin D needed per day varies by age. The chart below shows the often-cited recommendations of the Institute of Medicine, now the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine. It is important to know that these are general recommendations. If your doctor is checking your blood levels, he or she might recommend higher or lower doses based on your individual needs.
If you have osteoporosis, your doctor might suggest a blood test of your vitamin D levels. The amount of vitamin D supplement can be customized for each person, based on the results. For many older patients, a vitamin D supplement containing anywhere between 800 to 2000 IUs daily, which can be obtained without a prescription, can be both safe and beneficial. It is important to speak with your doctor about your individual needs.
People by ageRecommended dietary allowance (IU/day)Upper level intake (IU/day)Infants 0-6 months*4001,000Infants 6-12 months*4001,500Children 1-3 years old6002,500Children 4-8 years old6003,000People 9-70 years old6004,000People over 70 years old8004,000Females 14-50 years old, pregnant/lactating6004,000
*refers to adequate intake vs recommended dietary allowance of the other age groups.